What size bolts for post mount calipers?
The standard answer is two M6 bolts with a 1.0 mm thread pitch (M6 x 1.0), typically about 12–16 mm long, driven with a 4 mm Allen key. Always verify the exact specs for your caliper and frame, especially if you’re using adapters.
Understanding post mount calipers
Post mount brakes attach to dedicated mounting posts on a fork or frame, with holes spaced at a fixed interval. The most common spacing is 74 mm between the centers of the two posts. Some frames use adapters to convert to other standards, such as IS (International Standard) 51 mm, but the mounting bolts themselves are usually the same M6 size. The adapter choice can affect the effective bolt length and any required washers, so it’s important to check both the caliper and any adapters you’re using.
Typical bolt specifications you’ll encounter
Before listing the standard specs, note that there is variation by brand and model. The following baseline covers what you’re most likely to need for a standard post mount setup.
- M6 x 1.0 bolts for caliper mounting (two bolts per caliper).
- Common bolt length: 12–16 mm, depending on caliper design, rotor thickness, and any adapters in the install.
- Head type: usually a 4 mm Allen (hex) socket; some models may use Torx or a different hex size, so confirm with your specific caliper.
- Material options: stainless steel or high-tensile steel are typical; some aftermarket bolts may be titanium or other alloys, but compatibility and strength must be considered.
When using a post mount adapter (for example to fit a different rotor size or to convert IS to post mount), the effective bolt length may change because of added stack height. Always verify the correct bolt length for your exact combination of caliper, adapter, and frame.
Installation tips: torque and safety
Torque specifications vary by brand and model, but you’ll usually find a range around 6–12 N·m for caliper mounting bolts. A common target is 6–8 N·m for many road and MTB setups, but always consult the manufacturer’s service manual for your specific model. Use a torque wrench to ensure accuracy, and follow the guidance on whether threadlocker is recommended for your bolts.
Where to find the right specs
Consult the caliper’s user manual, the frame or fork installation guide, and any adapter documentation. If you’re replacing bolts, buy hardware labeled for caliper mounting (M6 x 1.0, typically 12–16 mm). Brands like Shimano and SRAM publish model-specific torque and length requirements in their service sheets, so use those as your primary reference.
Summary
For most post mount disc brakes, the typical mounting hardware is two M6 x 1.0 bolts, about 12–16 mm long, driven with a 4 mm Allen key. Always verify the exact bolts and torque from your caliper and frame manuals, especially when adapters are involved, to ensure safe and effective braking performance.
What is the torque for post mount calipers?
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Are caliper mounting bolts universal?
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What size are brake caliper mounting bolts?
The size of a brake caliper bracket bolt varies significantly by vehicle, so there is no single standard size. Common sizes include Metric (M12, M14, M16) and SAE (1/2 inch) options, with specific measurements like M12-1.5, M14-2.0, or 1/2-20, and different lengths. It is crucial to identify the correct size for your specific make and model to ensure a safe and proper fit.
To find the correct size for your vehicle
- Check your vehicle's service manual: This is the most reliable source for the correct specifications for your car.
- Measure your existing bolts: You can measure the diameter and thread pitch of the old bolts.
- Search online using your vehicle's information: Use your year, make, model, and specific brake component (e.g., "2018 Ford F-150 front brake caliper bracket bolt size").
- Purchase a kit or replacement bolt from an auto parts store: Many auto parts stores, like O'Reilly Auto Parts, sell replacement bolts or kits where you can specify your vehicle's details to find a match.
Common examples
- M12-1.25: This is a common thread size for some vehicles.
- M14-2.0: Used on some larger trucks or SUVs.
- M16-2.0: Another size that might be found on heavy-duty applications.
- 1/2 inch: SAE size commonly found on American vehicles, sometimes with a 1/2-20 thread pitch.
